Abstract Water soluble metal dithionites (often called hydrosulfites or hyposulfites) are valuable reducing agents for many chemical reactions such as textile dyeing, but the material must be either anhydrous and stored under an inert vapor, or supplied as an aqueous solution, in which case the material has limited stability in that the active material spontaneously decomposes in a short period of time, although the useful life of such solutions may be prolonged by refrigeration. If the crystals in the form in which they are precipitated are allowed to stand in the supernatant mother liquor, they eventually form a hard, concrete-like cake. The present invention provides a method of maintaining a dispersion of crystalline zinc or alkali metal dithionite hydrate in dispersed form by continuous or periodic mechanical agitation, the crystals being capable of storage for long periods without decomposition. The dispersing medium may be aqueous or nonaqueous and contains a material which suppresses dissolution of the dithionite solids.
IN A METHOD OF STORING AND SHIPPING ZINC OR ALKALI METAL DITHIONITE HYDRATE, THE IMPROVEMENT OF SUSPENDING FINELY DIVIDED PARTICLES THEREOF IN A LIQUID WHICH DOES NOT REACT THEREWITH OR CATALYZE THE DECOMPOSITION THEREOF, COMPRISING A MATERIAL WHICH SUPPRESSES THE DISSOLUTION OF THE PARTICLES IN THE LIQUID, THE MATERIAL BEING INERT WITH RESPECT TO THE DITHIONITE AND A NONSOLVENT THEREFOR, THE AMOUNT OF SAID MATERIAL BEING SUFFICIENT TO PREVENT DISSOLUTION OF SAID PARTICLES, THE PH OF THE LIQUID BEING AT LEAST 6.5 AND MAINTAINING SAID PARTICLES IN SUSPENDED OR RESUSPENDABLE FORM DURING STORAGE AND SHIPMENT THEREOF BY MEANS OF MECHI A ANCIAL AGITATION, THE VISCOSITY OF SAID DISPERSION BEING BELOW ABOUT 50,000 CENTIPOISES.
Claim 2
Dependent Claim
113 words
IN A METHOD OF STORING AND SHIPPING ZINC OR ALKALI METAL DITHIONITE HYDRATE, THE IMPROVEMENT OF SUSPENDING FINELY DIVIDED PARTICLES THEREOF IN A LIQUID WHICH DOES NOT REACT THEREWITH OR CATALYZE THE DECOMPOSITION THEREOF, COMPRISING A MATERIAL WHICH SUPPRESSES THE DISSOLUTION OF THE PARTICLES IN THE LIQUID, THE MATERIAL BEING INERT WITH RESPECT TO THE DITHIONITE AND A NONSOLVENT THEREFOR, THE AMOUNT OF SAID MATERIAL BEING SUFFICIENT TO PREVENT DISSOLUTION OF SAID PARTICLES, THE PH OF THE LIQUID BEING AT LEAST 6.5 AND MAINTAINING SAID PARTICLES IN SUSPENDED OR RESUSPENDABLE FORM DURING STORAGE AND SHIPMENT THEREOF BY MEANS OF MECHI A ANCIAL AGITATION, THE VISCOSITY OF SAID DISPERSION BEING BELOW ABOUT 50,000 CENTIPOISES.
Claim 3
Dependent Claim
25 words
The method of claim 1 in which said liquid is water containing an alkanol and an alkali metal or ammonium salt of an inorganic acid.
Claim 4
Dependent Claim
13 words
The method of claim 2 in which the pH is at least 9.